In the past two decades, the obesity rate of preschool-aged children in developed countries like the United States has increased at an alarming rate [34
]. Because obesity tends to track from childhood into adulthood, experts have recommended that obesity prevention be initiated as early as possible, particularly in preschool-aged children [36
]. PA and its counterpart, sedentary behavior, have been associated with the increased prevalence of obesity in children [37
]. Therefore, effective interventions designed to increase preschool-aged children’s PA levels are desperately needed.
Approximately, 58% preschoolers in the US spend the majority of their day in an early childcare program (i.e., preschool centers) [41
]. Therefore, early childcare programs present a unique opportunity to increase PA levels in this population. Due to the significant amount to time that preschoolers spend at the preschool setting, some states have started regulating PA policies. For example, in 2010, Massachusetts State Department of Early Education & Care mandated that preschool centers should provide a minimum of 60
min of daily gross motor playtime. Most preschools divide the 60-min block into two 30-min time blocks (one in the morning and one in the afternoon) of free unstructured playtime. Unfortunately, unstructured free playtime has been shown to have very little impact on preschooler’s PA levels [4
]. In addition, researchers have shown that preschoolers tend to accumulate only 8–12
min of MVPA during a typical 30-min gross motor playtime [6
In order to change the PA policy in preschoolers to increase the amount of MVPA in which they engage, changes are needed not only in the types of PA to which preschoolers are exposed, but also in the academic classroom. The STEP study examines the effects of short bouts of structured PA implemented within the classroom setting as part of designated gross motor playtime on during preschool total PA and sedentary time in preschoolers. We hypothesized that short bouts of PA just prior to engaging in outdoor activity can not only increase classroom PA, but can also increase the amount of MVPA in which children engage during unstructured playtime.
Of the 15 sites approached to participate in the program, we were able to successfully recruit 10 low-SES preschool centers. The established partnership with each preschool center allowed us to engage classroom teachers’ assistance in the recruitment of individual participants for the assessment portion of the study. The randomization process produced two groups with similar characteristics and only a few statistically significant differences. The number of significant differences identified between intervention and control groups in the current study could happen by chance. Most of the participants in the sample are of normal weight, however approximately 35% were classified as overweight/obese. The prevalence of overweight/obese status among preschool-aged children in the study sample is substantially higher than the reported prevalence (21.2%) in the 2007–2008 NHANES [34
]. We observed a statistically significant difference in body weight and BMI percentile values between the two groups, with the UPA group being heavier than participants in the SBS-PA group. Although significant, the absolute numbers between the two groups was small. The significant difference in these values will be taken into account in analyzing the effect of the SBS-PA intervention on PA due to the correlation between weight and PA. Researchers have reported that overweight/obese children tend to be less active than their normal weight/leaner counterparts [42
On average the participants in this study spent a large percentage of the preschool day in sedentary activity and only 6% of the time engaged in MVPA. Their reported baseline MVPA (accelerometer) level is similar to what others have reported in preschool-age children [4
]. OSRAC-P (direct observation system) was used to assess participants’ PA during gross motor playtime. We observed that during this time period, participants engaged in MVPA approximately 33% of the observed intervals, similar to what other researchers have reported (27-40%) [6
]. During the observed intervals, a significant between group difference was observed for light intensity activity. It is difficult to compare the PA data from accelerometery to that from direct observation because accelerometer data were collected for the entire preschool day and the direct observation data were only collected during gross motor playtime. To date classroom teachers have successfully implemented the TFIR
DVDs. These teachers who are usually pressed for time have reported an increased ability to use the TFIR
DVDs to expose the children to more structured bouts of physical activity.
Very few studies have been successful at increasing PA during the school day in preschool-aged children. Several states are passing non-funded regulatory PA policy mandating that preschool centers should provide a minimum of 60
min of daily gross motor playtime for preschool-aged children. However, most of these policies do not indicate how this time should be allocated. Most preschools divide the 60-min block into two 30-min time blocks (one in the morning and one in the afternoon) of free playtime (unstructured). But this approach does not increase PA [4
]. Researchers have observed that preschoolers spend an average of 27–40% of a 30-min outdoor playtime engaged in MVPA [6
]. The accumulation of MVPA during gross motor playtime generally occurs during the first half of playtime and represents a small fraction of the amount of time that preschoolers engage in MVPA. Based on this evidence, a better PA policy would be to expose preschoolers to shorter bouts of structured PA throughout the preschool day.